.\" netsniff-ng - the packet sniffing beast
.\" Copyright 2013 Daniel Borkmann.
.\" Subject to the GPL, version 2.
.TH ASTRACEROUTE 8 "03 March 2013" "Linux" "netsniff-ng toolkit"
.SH NAME
astraceroute \- autonomous system trace route utility
.PP
.SH SYNOPSIS
.PP
\fBastraceroute\fP [\fIoptions\fP]
.PP
.SH DESCRIPTION
astraceroute is a small utility to retrieve path information in a traceroute
like way, but with additional geographical location information. It tracks the
route of a packet from the local host to the remote host by successively
increasing the IP's TTL field, starting from 1, in the hope that each intermediate
node will send an ICMP TIME_EXCEEDED notification back to the local host when the
TTL value is decremented to 0.
.PP
astraceroute supports IPv4 and IPv6 queries and will display country and city
information, if available, the AS number the hop belongs to, and its
ISP name. astraceroute also displays timing information and reverse DNS data.
.PP
Due to astraceroute's configurability, it is also possible to gather some more
useful information about the hop regarding what it does and does not allow to pass
through. This is done by using clear text strings for probing DPIs or
``great firewalls'' to determine if they will filter out blocked critical
keywords. This tool might be a good start for further in-depth analysis
of such systems.
.PP
.SH OPTIONS
.TP
.B -H <host>, --host <host>
Hostname or IPv4 or IPv6 address of the remote host where the AS route should
be traced to. In the case of an IPv6 address or host, option \fB-6\fP must be
used. IPv4 is the default.
.TP
.B -p <port>, --port <port>
TCP port for the remote host to use. If not specified, the default
port used is 80.
.TP
.B -i <device>, -d <device>, --dev <device>
Networking device to start the trace route from, e.g. eth0, wlan0.
.TP
.B -b <IP>, --bind <IP>
IP address to bind to other than the network device's address. You must specify
\fB-6\fP for an IPv6 address.
.TP
.B -f <ttl>, --init-ttl <ttl>
Initial TTL value to be used. This option might be useful if you are not
interested in the first n hops, but only the following ones. The default
initial TTL value is 1.
.TP
.B -m <ttl>, --max-ttl <ttl>
Maximum TTL value to be used. If not otherwise specified, the maximum
TTL value is 30. Thus, after this has been reached astraceroute exits.
.TP
.B -q <num>, --num-probes <num>
Specifies the number of queries to be done on a particular hop. The
default is 2 query requests.
.TP
.B -x <sec>, --timeout <sec>
Tells astraceroute the probe response timeout in seconds, in other words
the maximum time astraceroute must wait for an ICMP response from the current
hop. The default is 3 seconds.
.TP
.B -X <string>, --payload <string>
Places an ASCII cleartext string into the packet payload. Cleartext that
contains whitespace must be put into quotes (e.g.: "censor me").
.TP
.B -l <len>, --totlen <len>
Specifies the total length of the packet. Payload that does not have a
cleartext string in it is padded with random garbage.
.TP
.B -4, --ipv4
Use IPv4 only requests. This is the default.
.TP
.B -6, --ipv6
Use IPv6 only requests. This must be used when passing an IPv6 host as an
argument.
.TP
.B -n, --numeric
Tells astraceroute to not perform reverse DNS lookup for hop replies. The
reverse option is \fB-N\fP.
.TP
.B -u, --update
The built-in geo-database update mechanism will be invoked to get Maxmind's
latest version. To configure search locations for databases, the file
/etc/netsniff-ng/geoip.conf contains possible addresses. Thus, to save bandwidth
or for mirroring Maxmind's databases (to bypass their traffic limit policy),
different hosts or IP addresses can be placed into geoip.conf, separated by
a newline.
.TP
.B -L, --latitude
Also show latitude and longitude of hops.
.TP
.B -N, --dns
Tells astraceroute to perform reverse DNS lookup for hop replies. The
reverse option is \fB-n\fP.
.TP
.B -S, --syn
Use TCP's SYN flag for the request.
.TP
.B -A, --ack
Use TCP's ACK flag for the request.
.TP
.B -F, --fin
Use TCP's FIN flag for the request.
.TP
.B -P, --psh
Use TCP's PSH flag for the request.
.TP
.B -U, --urg
Use TCP's URG flag for the request.
.TP
.B -R, --rst
Use TCP's RST flag for the request.
.TP
.B -E, --ecn-syn
Use TCP's ECN flag for the request.
.TP
.B -t <tos>, --tos <tos>
Explicitly specify IP's TOS.
.TP
.B -G, --nofrag
Set IP's no fragmentation flag.
.TP
.B -Z, --show-packet
Show and dissect the returned packet.
.TP
.B -v, --version
Show version information and exit.
.TP
.B -h, --help
Show user help and exit.
.PP
.SH USAGE EXAMPLE
.TP
.B astraceroute -i eth0 -N -S -H netsniff-ng.org
This sends out a TCP SYN probe via the ''eth0'' networking device to the
remote IPv4 host netsniff-ng.org. This request is most likely to pass. Also,
tell astraceroute to perform reverse DNS lookups for each hop.
.TP
.B astraceroute -6 -i eth0 -S -E -N -H www.6bone.net
In this example, a TCP SYN/ECN probe for the IPv6 host www.6bone.net is being
performed. Also in this case, the ''eth0'' device is being used as well as a
reverse DNS lookup for each hop.
.TP
.B astraceroute -i eth0 -N -F -H netsniff-ng.org
Here, we send out a TCP FIN probe to the remote host netsniff-ng.org. Again,
on each hop a reverse DNS lookup is being done and the queries are transmitted
from ''eth0''. IPv4 is used.
.TP
.B astraceroute -i eth0 -N -FPU -H netsniff-ng.org
As in most other examples, we perform a trace route to IPv4 host netsniff-ng.org
and do a TCP Xmas probe this time.
.TP
.B astraceroute -i eth0 -N -H netsniff-ng.org -X "censor-me" -Z
In this example, we have a Null probe to the remote host netsniff-ng.org, port
80 (default) and this time, we append the cleartext string "censor-me" into the
packet payload to test if a firewall or DPI will let this string pass. Such a trace
could be done once without and once with a blocked string to gather possible
information about censorship.
.PP
.SH NOTE
If a TCP-based probe fails after a number of retries, astraceroute will
automatically fall back to ICMP-based probes to pass through firewalls
and routers used in load balancing for example.
.PP
To gather more information about astraceroute's displayed AS numbers, see e.g.:
http://bgp.he.net/AS<number>.
.PP
.SH BUGS
The geographical locations are estimated with the help of Maxmind's GeoIP
database and can differ from the real physical location. To decrease the
possible errors, update the database regularly using astraceroute's
\fB--update\fP option.
.PP
At some point in time, we need a similar approach to gather more reliable path
information such as in the paris-traceroute tool.
.PP
Due to the generic nature of astraceroute, it currently has a built-in mechanism
to stop the trace after a fixed number of hops, since the configurable TCP flags
can have anything included. It is possible to decrease this number of course.
In the future, if a SYN probe is sent out, there should be a listener so that we can
stop the trace if we detect a handshake in progress.
.PP
.SH LEGAL
astraceroute is licensed under the GNU GPL version 2.0.
.PP
.SH HISTORY
.B astraceroute
was originally written for the netsniff-ng toolkit by Daniel Borkmann. It
is currently maintained by Tobias Klauser <tklauser@distanz.ch> and Daniel
Borkmann <dborkma@tik.ee.ethz.ch>.
.PP
.SH SEE ALSO
.BR netsniff-ng (8),
.BR trafgen (8),
.BR mausezahn (8),
.BR ifpps (8),
.BR bpfc (8),
.BR flowtop (8),
.BR curvetun (8)
.PP
.SH AUTHOR
Manpage was written by Daniel Borkmann.
.PP
.SH COLOPHON
This page is part of the Linux netsniff-ng toolkit project. A description of the project,
and information about reporting bugs, can be found at http://netsniff-ng.org/.
